What oxygen concentration is considered dangerous?

What oxygen concentration is considered dangerous?

• A. Below 7%
• B. Above 21%
• C. Between 10% and 15%
• D. Exactly 19.5%

Answer: (A)

Low oxygen levels are the most dangerous because the body can’t get enough oxygen to tissues, leading to rapid impairment and loss of consciousness. Normal air has about 21% oxygen; as the concentration drops, especially into the single digits, the risk of serious harm increases quickly. Below 7% oxygen means a severe deficiency that can cause quick collapse and life-threatening situations without immediate intervention. The other options describe higher or near-normal levels that are not as acutely hazardous in everyday safety contexts.

Low oxygen levels are the most dangerous because the body can’t get enough oxygen to tissues, leading to rapid impairment and loss of consciousness. Normal air has about 21% oxygen; as the concentration drops, especially into the single digits, the risk of serious harm increases quickly. Below 7% oxygen means a severe deficiency that can cause quick collapse and life-threatening situations without immediate intervention. The other options describe higher or near-normal levels that are not as acutely hazardous in everyday safety contexts.